Semiconductor device, semiconductor module and hard disk

ABSTRACT

A heat radiation electrode ( 15 ) is exposed from the back surface of an insulating resin ( 13 ), and a metal plate ( 23 ) is affixed to this heat radiation electrode ( 15 ). The back surface of this metal plate ( 23 ) and the back surface of a flexible sheet become substantially within a same plane, so that it is readily affixed to a second supporting member ( 24 ). In addition, the top surface of the heat radiation electrode ( 15 ) is made protrusive beyond the top surfaces of the pads ( 14 ) to reduce the distance between the semiconductor chip ( 16 ) and the heat radiation electrode ( 15 ). Accordingly, the heat generated by the semiconductor chip can be efficiently dissipated via the heat radiation electrode ( 15 ), the metal plate ( 23 ) and the second supporting member ( 24 ).

This is a divisional from parent application Ser. No. 09/809,857 filedMar. 16, 2001, now U.S. Pat. No. 6,646,331, which, in turn, claims thebenefit of Japanese application serial no. 2000-306670 filed Oct. 5,2000.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device, a semiconductormodule and a hard disk, and especially to a structure capable ofefficiently dissipating heat from a semiconductor chip.

Due to the recent growth of the use of semiconductor devices in portabledevices and small/densely-mounted devices, the reduction in size andweight and the improvement in heat dissipation properties are demandedat the same time. In addition, semiconductor devices are mounted onvarious types of substrates, which, in turn, are mounted in various manysystems as semiconductor modules. As for such a substrate, the use of aceramic substrate, a printed board, a flexible sheet, a metal substrateor a glass substrate etc. may be contemplated, and the followingdescription gives one example thereof. Here, the semiconductor module isexplained as being mounted on a flexible sheet.

FIG. 17 shows an example in which a semiconductor module using aflexible sheet is mounted in a hard disk 100. This hard disk 100 may be,for example, the one described in detail in an article of NikkeiElectronics (No. 691, Jun. 16, 1997, p.92-).

This hard disk 100 is accommodated within a casing 101 made of a metal,and comprises a plurality of recording disks 102 that are integrallyattached to a spindle motor 103. Over the surfaces of individualrecording disks 102, magnetic heads 104 are respectively disposed eachwith a very small clearance. These magnetic heads 104 are attached atthe tips of suspensions 106 which are affixed to the ends of respectivearms 105. A magnetic head 104, a suspension 106 and an arm 105 togetherform one integral body and this integral body is attached to an actuator107.

the magnetic heads 104 must be electrically connected with a read/writeamplifying IC 108 in order to perform read and write operations.Accordingly, a semiconductor module comprising this read/writeamplifying IC 108 mounted on a flexible sheet 109 is used, and thewirings provided on this flexible sheet 109 are electrically connected,ultimately, to the magnetic heads 104. This semiconductor module 110 iscalled “flexible circuit assembly”, typically abbreviated as “FCA”.

From the back surface of the casing 101, connectors 111 provided on thesemiconductor module 110 are exposed, and these connector (male orfemale) 111 and connectors (female or male) attached on a main board 112are engaged. On this main board 112, wirings are provided, and drivingICs for the spindle motor 103, a buffer memory and other ICs for adriving, such as ASIC, are mounted.

The recording disk 102 spins at, for example, 4500 rpm via the spindlemotor 103, and the actuator 107 detects the position of the magnetichead 104. Since this spinning mechanism is enclosed by a cover providedover the casing 101, there is no way to completely prevent theaccumulation of heat, resulting in the temperature rise in theread/write amplifying IC 108. Therefore, the read/write amplifying IC108 is attached to the actuator 107 or the casing 101 etc. at a locationhaving a better heat conduction property than elsewhere. Further, sincerevolutions of the spindle motor 103 tend to high speed such as 5400,7200 and 10000 rpm, this heat dissipation has more importance.

In order to provide further detail of the FCA explained above, thestructure thereof is shown in FIG. 18. FIG. 18A is the plan view, andFIG. 18B is a cross-sectional view taken along the line A—A which cutsacross the read/write amplifying IC 108 provided on one end of themodule. This FCA 110 is attached to an internal portion of the casing101 in a folded-state, so that it employs a first flexible sheet 109have a two-dimensional shape that can easily be folded.

On the left end of this FCA 110, the connectors 111 are attached,forming a first connection section 120. First wirings 121 electricallyconnected to these connectors 111 are adhered on the first flexiblesheet 109, and they extend all the way to the right end. The firstwirings 121 are then electrically connected to the read/write amplifyingIC 108. Leads 122 of the read/write amplifying IC 108 to be connected tothe magnetic heads 104 are connected with second wirings 123 which, inturn, are electrically connected to third wirings 126 on a secondflexible sheet 124 provided over the arm 105 and suspension 106. Thatis, the right end of the first flexible sheet 109 forms a secondconnection section 127 at which the first flexible sheet 109 isconnected to the second flexible sheet 124. Alternatively, the firstflexible sheet 109 and the second flexible sheet 124 may be integrallyformed. In this case, the second wirings 123 and the third wirings 126are provided integrally.

On the back surface of the first flexible sheet 109 on which theread/write amplifying IC 108 is to be provided, a supporting member 128is disposed. As for this supporting member 128, a ceramic substrate oran Al substrate may be used. The read/write amplifying IC 108 isthermally coupled with a metal that is exposed to inside of the casing101 through this supporting member 128, so that the heat generated inthe read/write amplifying IC 108 can be externally released.

With reference to FIG. 18B, a connecting structure between theread/write amplifying IC 108 and the first flexible sheet 109 will nowbe explained.

This flexible sheet 109 is constituted by laminating, from the bottom, afirst polyimide sheet 130 (first PI sheet), a first adhesion layer 131,a conductive pattern 132, a second adhesion layer 133 and a secondpolyimide sheet 134 (second PI sheet), so that the conductive pattern132 is sandwiched between the first and second PI sheets 130 and 134.

In order to connect the read/write amplifying IC 108, a portion of thesecond PI sheet 134 and the second adhesion layer 133 are eliminated atthe connection section to form an opening 135 which exposes theconductive pattern 132. The read/write amplifying IC 108 is electricallyconnected thereto through leads 122 as shown in the figure.

The semiconductor device packaged by an insulating resin 136 as shown inFIG. 18B has heat dissipating paths indicated by arrows for externallydissipating its heat. Especially, since the insulating resin 136 givesthe thermal resistance, the semiconductor device has a structure thatthe heat generated by the read/write amplifying IC 108 cannot beefficiently dissipated to the outside the device.

Further details will now be explained using this example in hard diskapplication. As for the read/write transfer rate of a hard disk, afrequency of 500 MHz to 1 GHz, or even a greater frequency, is required,so that the read/write speed of the read/write amplifying IC 108 must befast. To this end, the paths of the wirings on the flexible sheet thatare connected to the read/write amplifying IC 108 has to be shorten, andthe temperature rise in the read/write amplifying IC 108 must besuppressed.

Especially, since the recording disks 102 are spinning at a high speed,and the casing 101 and the lid provide a molded space, the interiortemperature would rise up to around 70 to 80° C. On the other hand, atypical allowable temperature for the operation of an IC isapproximately 125° C. This means that, from the interior temperature of80° C., a further temperature rise by approximately 45° C. ispermissible for the read/write amplifying IC 108. However, where thethermal resistance of the semiconductor device itself and FCA is large,this allowable operation temperature can easily be exceeded, therebydisabling the device to provide its actual performance level.Accordingly, a semiconductor device and FCA having superior heatdissipating properties are being demanded.

Furthermore, since the operation frequency is expected to furtherincrease in the future, further temperature rise is also expected in theread/write amplifying IC 108 itself due to the heat generated bycomputing operations. At room temperature, the IC can provide theperformance at its intended operation frequency, however, where it isplaced inside of a hard disk, its operation frequency has to be reducedin order to restrain the temperature rise.

As described above, further heat dissipating properties of semiconductordevice, semiconductor module (FCA) are demanded in connection with theincrease of the operation frequency in the future.

On the other hand, the actuator 107, and the arms 105, suspensions 106and magnetic heads 104 attached thereto has to be designed aslight-weighted as possible in order to reduce the moment of inertia.Especially, where the read/write amplifying IC 108 is mounted on thesurface of the actuator 107 as shown in FIG. 17, the weight reduction isdemanded also for the IC 108 and FCA 110.

SUMMARY OF THE INVENTION

The present invention was invented in consideration with the aboveproblems, and in the first aspect, it provides a semiconductor devicecomprising a semiconductor chip integrally molded with an insulatingresin in a face-down state, the semiconductor device having exposed onthe back surface thereof a pad electrically connected to a bondingelectrode of the semiconductor chip and a heat radiation electrodedisposed over the surface of the semiconductor chip, wherein the problemis solved by having the top surface of the heat radiation electrodeprotrude beyond the top surface of the pad, and practically determiningthe thickness of a connecting means for connecting the bonding electrodeand the pad by the amount of this protrusion.

As for the means to connect the pad and the bonding electrode, an Aubump or a solder ball maybe used. The Au bump may comprise at least onestage of an Au cluster, and the thickness thereof would be about 40 μmfor a one-stage bump and 70-80 μm for a two-stage bump. Since the heightof the heat radiation electrode surface generally matches with theheight of the pad surface, the space between the semiconductor chip andthe heat radiation electrode is determined by the thickness of the bump.Accordingly, the space between the semiconductor chip and the heatradiation electrode cannot be made any smaller than the thickness of thebump. However, if the surface of the heat radiation electrode isdesigned to protrude beyond the surface of the pad by the substantialthickness of the bump, the space may be made smaller.

The thickness of a solder bump or a solder ball is approximately 50 to70 μm, and in this case also, the space may be made small according tothe same principle. A brazing material such as solder has a goodwettability with the pad, so that when it is in a molten state, itspreads out over the surface of the pad, resulting in a smallerthickness. However, since the gap between the bonding electrode and thepad is determined by the amount of protrusion of the heat radiationelectrode, the thickness of the brazing material is determined by thisamount of the protrusion. Accordingly, by the amount the brazingmaterial can be made thicker, then the stress applied to the solder bumpmay be more distributed, so that the deterioration due to heat cyclescan be minimized.

In the second aspect, the problem is solved by using an Au bump or abump of a brazing material such as solder or a solder ball as theconnecting means.

In the third aspect, the problem is solved by providing a metal plate onthe exposed portion of the heat radiation electrode in a manner so thatit protrudes beyond the back surface of the pad.

This protrusive metal plate and the back surface of a flexible sheetwhich serves as a first supporting member may be made within a sameplane, so that a structure is provided, in which the metal plate can beadhered or abutted to the interior of a casing, especially to a memberof the casing having a flat surface such as a heat sink plate etc.

In the fourth aspect, the problem is solved by disposing the backsurface of the pad and the back surface of the heat radiation electrodesubstantially within a same plane.

In the fifth aspect, the problem is solved by affixing the semiconductorchip and the heat radiation electrode together by an insulatingmaterial.

In the sixth aspect, the problem is solved by affixing the heatradiation electrode and the metal plate together by an insulatingmaterial or a conductive material.

In the seventh aspect, the problem is solved by integrally forming theheat radiation electrode and the metal plate from a same material.

In the eighth aspect, the problem is solved by having the back surfaceof the insulating resin protrude beyond the back surface of the pad.

When forming a brazing material such as solder over the back surface ofthe pad, the thickness of the solder may be determined by the amount ofthis protrusion. It also prevents short-circuiting with the conductivepattern extending over the back surface of the semiconductor device.

In the ninth aspect, the problem is solved by having the side surfacesof the pad and the back surface of the insulating resin that extendsfrom the side surfaces of the pad define a same curved surface.

The insulating resin exposed from the back surface of the semiconductordevice would define a curved surface when etched, and would exhibit ashape which provides a point contact rather than a face contact.Accordingly, the frictional resistance of the back surface of thesemiconductor device is reduced, thereby facilitating self-alignment. Italso provides a relief for the brazing material which is more effectivecomparing to a structure in which the protrusive feature of the backsurface of the insulating resin is flat. In this way theshort-circuiting between the adjacent bumps of the brazing material maybe avoided.

In the tenth aspect, a semiconductor module is provided, which comprisesa first supporting member having a conductive pattern provided thereonand a semiconductor device comprising a semiconductor chip which iselectrically connected to the conductive pattern and is integrallymolded by an insulating resin in a face-down state, the semiconductordevice having exposed on the back surface thereof, a pad electricallyconnected to a bonding electrode of the semiconductor chip and a heatradiation electrode disposed over the surface of the semiconductor chip,wherein the problem is solved by having the top surface of the heatradiation electrode protrude beyond the top surface of the pad, anddetermining the thickness of a connecting means for connecting thebonding electrode and the pad according to the amount of thisprotrusion, an by electrically connecting the pad to the conductivepattern provided on the first supporting member, and providing anopening to the first supporting member at a location which correspondsto the heat radiation electrode, the opening accommodating a metal platewhich is affixed to the heat radiation electrode.

The distance between the semiconductor chip and the heat radiationelectrode can be set so as to assure the conduction of heat, and at thesame time, the metal plate thermally coupled with the heat radiationelectrode can be abutted to a heat-dissipating substrate provided underthe first supporting member.

In the eleventh aspect, the problem is solved by adhering a secondsupporting member having the metal plate affixed thereto to the backsurface of the first supporting member, and affixing this metal plateand the heat radiation electrode together.

In the twelfth aspect, the problem is solved by forming the heatradiation electrode and the metal plate integrally from a same material.

As shown in FIGS. 13 and 14, the metal plate and the heat radiationelectrode may be formed integrally by etching a conductive foil, therebyunnecessitating the step for affixing the metal plate.

In the thirteenth aspect, the problem is solved by providing a fixationplate made of a conductive material over the second supporting member ata location which corresponds to the metal plate, and by thermallycoupling the fixation plate and the metal plate.

In the fourteenth aspect, the problem is solved by forming,respectively, the metal plate mainly by Cu, the second supporting membermainly by Al, and the fixation plate by a plated film mainly made of Cuformed on the second supporting member.

In this way, the thermal resistance between the second supporting memberand the fixation plate may substantially be reduced, so that thetemperature rise in the semiconductor chip may be effectively prevented.

In the fifteenth aspect, the problem is solved by having the backsurface of the insulating resin protrude beyond the back surface of thepad.

In the sixteenth aspect, the problem is solved by having the sidesurfaces of the pad and the back surface of the insulating resin whichextends from the side surfaces of the pad define the same curvedsurface.

In the seventeenth aspect, the problem is solved by using thesemiconductor chip as a read/write amplifying IC for a hard disk.

In the eighteenth aspect, a semiconductor device is provided, whichcomprises a semiconductor chip integrally molded by an insulating resinin a face-down state, the semiconductor device having exposed on theback surface thereof, a pad electrically connected to a bondingelectrode of the semiconductor chip, an external electrode extending viaa wiring integral with the pad, and a heat radiation electrode disposedon the surface of the semiconductor chip, wherein the problem is solvedby having the top surface of the heat radiation electrode protrudebeyond the top surface of the pad, and determining the thickness of aconnecting means for connecting the bonding electrode and the padpractically by the amount of this protrusion.

In the nineteenth aspect, the problem is solved by using an Au bump or abump made of a brazing material such as solder, or a solder ball.

In the twentieth aspect, the problem is solved by disposing a metalplate over the exposed portion of the heat radiation electrode in amanner so that it protrudes beyond the back surface of the externalconnection electrode.

In the twenty-first aspect, the problem is solved by disposing the backsurface of the external connection electrode and the back surface of theheat radiation electrode substantially within a same plane.

In the twenty-second aspect, the problem is solved by affixing the heatradiation electrode and the metal plate together by an insulatingmaterial.

In the twenty-third aspect, the problem is solved by affixing the heatradiation electrode and the metal plate together by an insulatingmaterial or a conductive material.

In the twenty-fourth aspect, the problem is solved by integrally formingthe heat radiation electrode and the metal plate from a same material.

In the twenty-fifth aspect, the problem is solved by having the backsurface of the insulating resin protrude beyond the back surface of theexternal connection electrode.

In the twenty-sixth aspect, the problem is solved by having the sidesurfaces of the external connection electrode and the back surface ofthe insulating material which extends from the side surfaces of theexternal connection electrode define a same curved surface.

In the twenty-seventh aspect, a semiconductor module is provided, whichcomprises a first supporting member having a conductive pattern providedthereon, and a semiconductor device including a semiconductor chip whichis electrically connected to the conductive pattern and is integrallymolded by an insulating resin in a face-down state, the semiconductordevice having exposed on the back surface thereof, a pad electricallyconnected to a bonding electrode of the semiconductor chip, an externalconnection electrode provided via a wiring integral with the pad and aheat radiation electrode disposed over the surface of the semiconductorchip, wherein the problem is solved by having the top surface of theheat radiation electrode protrude beyond the top surface of the pad, anddetermining the thickness of a connecting means for connecting thebonding electrode and the pad practically by the amount of thisprotrusion, and by electrically connecting the conductive patternprovided on the first supporting member and the external connectionelectrode, and providing an opening in the first supporting member at alocation corresponding to the heat radiation electrode, the openingaccommodating a metal plate affixed to the heat radiation electrode.

In the twenty-eighth aspect, the problem is solved by adhering a secondsupporting member having the metal plate affixed thereto onto the backsurface of the first supporting member.

In the twenty-ninth aspect, the problem is solved by integrally formingthe heat radiation electrode and the metal plate from a same material.

In the thirtieth aspect, the problem is solved by providing a fixationplate made of a conductive material on the second supporting member at alocation corresponding to the metal plate, and by thermally coupling thefixation plate and the metal plate.

In the thirty-first aspect, the problem is solved by forming,respectively, the metal plate mainly by Cu, the second supporting membermainly by Al and the fixation plate by a plated film mainly made of Cuformed on the second supporting member.

In the thirty-second aspect, the problem is solved by having the backsurface of the insulating adhesive means protrude beyond the backsurface of the external connection electrode.

In the thirty-third aspect, the problem is solved by having the sidesurfaces of the external connection electrode and the insulatingadhesive means extending from the side surfaces of the externalconnection electrode define a same curved surface.

In the thirty-fourth aspect, the problem is solved by using thesemiconductor chip as a read/write amplifying IC for a hard disk.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a semiconductor module according to thepresent invention.

FIG. 2 is a diagram illustrating a semiconductor device according to thepresent invention.

FIG. 3 is a diagram illustrating a semiconductor device according to thepresent invention.

FIG. 4 is a diagram illustrating a manufacturing step of a semiconductordevice according to the present invention.

FIG. 5 is a diagram illustrating a manufacturing step of a semiconductordevice according to the present invention.

FIG. 6 is a diagram illustrating a manufacturing step of a semiconductordevice according to the present invention.

FIG. 7 is a diagram illustrating a manufacturing step of a semiconductordevice according to the present invention.

FIG. 8 is a diagram illustrating a manufacturing step of a semiconductordevice according to the present invention.

FIG. 9 is a diagram illustrating a semiconductor device of the presentinvention.

FIG. 10 is a diagram illustrating a film for preventing the running of amaterial, which is formed on the conductive pattern.

FIG. 11 is a diagram illustrating a semiconductor module of the presentinvention.

FIG. 12 is a diagram illustrating a manufacturing step of asemiconductor device according to the present invention.

FIG. 13 is a diagram illustrating a manufacturing step of thesemiconductor device according to the present invention.

FIG. 14 is a diagram illustrating a manufacturing step of thesemiconductor device according to the present invention.

FIG. 15 is a diagram illustrating a semiconductor device according tothe present invention.

FIG. 16 shows a series of diagrams illustrating several methods forforming a connection structure of the semiconductor chip and the pads.

FIG. 17 is a diagram illustrating a hard disk.

FIG. 18 is a diagram illustrating a conventional art semiconductormodule used in the hard disk of FIG. 17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a thin and small semiconductor devicehaving a superior heat-dissipating capability, and a semiconductormodule having this semiconductor device mounted thereon, such as asemiconductor module attached on a flexible sheet (hereinafter referredto as “FCA”), thereby providing improvement in the characteristics of,for example, a hard disk.

First, reference shall be made to FIG. 17 illustrating an exemplary harddisk in which such an FCA is implemented, and then to FIG. 1 showing theFCA. A semiconductor device mounted on this FCA and the manufacturingmethod thereof are shown in FIGS. 2 through 16.

(Embodiment 1)

The first embodiment is provided to illustrate an apparatus in which theFCA is implemented. As for this apparatus, the exemplary hard disk 100shown in FIG. 17 that has been used for illustrating the conventionalart will again be used.

The hard disk 100 may be mounted on a main board 112 as necessary inorder to place it in a computer etc. This main board 112 includes female(or male) connectors. Male (or female) connectors 111 provided on theFCA and exposed from the back surface of the casing 101 are connectedwith these connectors on the main board 112. Within the casing 101, aplurality of recording disks 102 used as a recording medium are providedin a number corresponding to the storage capacity of the hard disk.Since each of the magnetic heads 104 floats and scans over each of therecording disks 102 at a position approximately 20 nm to 30 nm away fromthe disk, the interval between the recording disks 102 are designed soas to allow this scanning to be undisturbed. The disks are attached to aspindle motor 103 at this interval. This spindle motor 103 is mounted ona mounting board, and a connector arranged on the back surface of thismounting board is exposed from the back surface of the casing 101. Thisconnector is connected to a connector of the main board. Accordingly,mounted on this main board 112 are, an IC for driving the read/writeamplifying IC 108 for the magnetic heads 104, an IC for driving thespindle motor 103, an IC for driving an actuator, a buffer memory fortemporarily storing data, and other ASICs etc. for implementing themanufacturer's own driving scheme. Of cause, any additional active andpassive elements may also be mounted.

The wirings connecting between the magnetic heads 104 and the read/writeamplifying IC 108 are designed to be as short as possible, so that theread/write amplifying IC 108 is disposed over the actuator 107. However,since the semiconductor device hereinafter explained is extremely thinand light-weighted, it may be mounted over the arm 105 or the suspension106 instead of the actuator. In this case, as shown in FIG. 1B, the backsurface of the semiconductor device 10 exposes from the opening 12 ofthe first supporting member 11, and the back surface of thesemiconductor device 10 is thermally coupled with the arm 105 or thesuspension 106, so that the heat from the semiconductor device 10 isexternally dissipated via the arm 105 and the casing 101.

Where the read/write amplifying IC 108 is mounted on the actuator 107 asshown in FIG. 17, the circuits for reading and writing respectivechannels are formed on a single chip so as to allow the plurality ofmagnetic sensors to read and write. However, a dedicated read/writecircuit may be mounted on each of the suspensions 106 for each of themagnetic heads 104 that are attached to the respective suspension 106.In this way, the wiring distance between a magnetic head 104 and aread/write amplifying IC 108 may be far shorter than that of thestructure shown in FIG. 18, and such a short distance would reduce theimpedance, resulting in an improved read/write rate. Since in thisexample, an application to a hard disk is assumed, a flexible sheet hasbeen selected for the use as the first supporting member, however,depending on the types of the apparatus, a printed board, a ceramicsubstrate or a glass substrate may instead be selected as the firstsupporting member.

(Embodiment 2)

The semiconductor device according to the second embodiment of thepresent invention will now be explained with reference to FIG. 2. FIG.2A is a plan view of the semiconductor device, and FIG. 2B is across-sectional view taken along the ling A—A. FIG. 2C is a diagram forillustrating the reason for providing the protrusive heat radiationelectrode 15.

In FIG. 2, the following elements are shown as embedded within aninsulating resin 13; pads 14, a heat radiation electrode 15 providedwithin a region surrounded by these bonding pads 14, and a semiconductorchip 16 disposed over the heat radiation electrode 15. The semiconductorchip 16 is mounted in a face-down state, and using an insulatingadhesive means 17 it is affixed to the heat radiation electrode 15 whichis divided into four pieces in order to achieve good adhesion. Theisolation trenches formed by this division are indicated by the numeral18A. Where the gap between the semiconductor chip 16 and the heatradiation electrode 15 is so small that the intrusion of the insulatingadhesive means 17 is disturbed, then trenches 18B that are shallowerthan the aforementioned isolation trenches 18A may be formed on thesurface of the heat radiation electrode 15.

The bonding electrodes 19 of the semiconductor chip 16 and the pads 14are electrically connected via connections 20 made of a brazing materialsuch as solder. Alternatively, stud bumps of Au may also be used in theplace of solder.

There are other types of connecting methods for achieving theseconnections. For example, after bumps are provided on the respectivebonding electrodes 19 of the semiconductor chip, the connections may beobtained through the application of ultrasonic wave to these bumps orthrough pressure welding. Also, at the peripheries of thepressure-welded bumps, solder, a conductive paste or anisotropicconductive particles may be provided. The greater details of thesestructures will be provided at the end of this embodiment section.

The back surfaces of the pads 14 are exposed from the insulating resin13, and as they are, form external connection electrodes 21, and theside surfaces of the pads 14 are etched non-anisotropically. Theseetched portions are formed by a wet etching method, so that they have acurved structure which promotes an anchor effect.

The present structure is constituted by five elements including thesemiconductor chip 16, a plurality of conductive patterns 14, the heatradiation electrode 15, the insulating adhesive means 17, and theinsulating resin 13 within which all the former elements are embedded.Within a region for disposing the semiconductor chip 16, the insulatingadhesive means 17 is formed over and between the pieces of the heatradiation electrode 15, especially within the isolation trenches 18formed by etching, so that the back surface of the insulating adhesivemeans is exposed from the back surface of the semiconductor device 10A.All the elements including the above are molded within the insulatingresin 13. The pads 14, heat radiation electrode 15 and semiconductorchip 16 are supported by the insulating resin 13 and the insulatingadhesive means 17.

As for the insulating adhesive means 17, an adhesive made of aninsulating material or an under fill material is preferable. Where anadhesive is employed, it may be applied to the surface of thesemiconductor chip 16 in advance, and cured as the pads 14 are connectedusing Au bumps instead of solder 20. In the case of an under fillmaterial 17, it may be injected into the gap after the solder 20 (orbumps) and pads 14 are connected.

As for the insulating resin, a heat-curable resin such as epoxy resin,or a thermoplastic resin such as polyimide resin or polyphenylenesulfide etc. may be used.

Any resin material can be used as the insulating resin 13 as long as itcan be cured using a metal mold, or can be applied by dipping orcoating. For the conductive pattern 14, a conductive foil mainly made ofCu, a conductive foil mainly made of Al or an Fe—Ni alloy, a laminate ofAl—Cu, Al—Cu—Al or Cu—Al—Cu, or the like maybe used. Of course any otherconductive material may also be used, and especially desirable are thoseconductive materials that can be etched, or that can be evaporated bylaser. Where the half-etching, plating and thermal stresscharacteristics are concerned, a conductive material mainly made of Cuformed through rolling is suitable.

According to the present invention, the trenches 18 and 22 are alsofilled with the insulating resin 13 and the insulating adhesive means 17so that slipping-out of the conductive pattern may be prevented. Also,by performing non-anisotropic etching through a dry-etch or wet-etchmethod, the side surfaces of the bonding pads 14 may be processed tohave a curved structure thereby promoting the anchor effect. Thisrealizes a structure that would not allow the conductive pattern 14 andheat radiation electrode 15 to slip out from the insulating resin 13.

Moreover, the back surface of the heat radiation electrode 15 is exposedfrom the back surface of the package. Therefore, the back surface of theheat radiation electrode 15 would form a structure that can be abuttedor attached to the later-described metal plate 23, the second supportingmember 24 or a fixation plate 25 formed on the second supporting member24. Accordingly, this structure allows the heat generated by thesemiconductor chip 16 to be dissipated into the second supporting member24, thereby preventing the temperature rise in the semiconductor chip 16so that the driving current and driving frequency of the semiconductorchip 16 may be increased.

In the semiconductor device 10A, since the pads 14 and the heatradiation electrode 15 are supported by the insulating resin 13, whichis a mold resin, the use of any supporting substrate is unnecessitated.This structure is one feature of the present invention. The conductivepaths of the conventional art semiconductor device are supported by asupporting substrate (flexible sheet, printed board or ceramicsubstrate), or by a lead frame, and this means that the conventional artdevice includes those elements that could potentially be unnecessitated.On the other hand, the device of the present invention is constituted byonly essential, minimal elements, and it eliminates the need for asupporting substrate, thus it can be made thin and light-weighted, andat the same time, its cost may be reduced as it require less materialcost. Accordingly, as explained in the description of the firstembodiment, it may be mounted on the arms or suspensions of a hard disk.

From the back surface of the package, the pads 14 and the heat radiationelectrode 15 are exposed. Where a brazing material such as solder isapplied over these regions, since the area of the heat radiationelectrode 15 is larger, the thickness of the applied brazing materialbecomes uneven. Accordingly, in order to make the film thickness of thebrazing material even, an insulating film 26 is formed on the backsurface of the semiconductor device 10A. The regions surrounded bydotted lines 27 shown in FIG. 2A indicate the portions of the heatradiation electrode 15 exposed from the insulating film 26, and theseportions are exposed in the same manner as the exposed square-shapedportions of the back surfaces of the bonding pads 14, the individualpotions of the heat radiation electrode 15 exposed from the insulatingfilm 26 and the exposed portions of the bonding pads 14 have the samesize.

Thus, the sizes of the portions wettable by the brazing material aresubstantially identical so that the brazing material formed theretowould have substantially the same thickness. This would not change evenafter a solder print or reflow process. The same is true for aconductive paste of i.e. Ag, Au or Ag—Pd etc. Given this structure, moreaccurate calculation can be performed to determine how much the backsurface of the metal plate 23 should protrude beyond the back surfacesof the pads 14.

When the metal plate 23 and the conductive pattern 32 are designed toalign within a same plane, then both the pads 14 and the heat radiationelectrode 15 may be soldered at once.

The exposed portions 27 of the heat radiation electrode 15 may be formedto have a larger size than that of the exposed portions of the bondingpad in consideration with the capability to dissipate the heat from thesemiconductor chip.

The provision of the insulating film 26 also allows the conductivepattern 32 provided on the first supporting member 11 to be disposedover the back surface of the semiconductor device. Generally, theconductive pattern 32 provided on the first supporting member 11 is soarranged that it bypasses the region over which the semiconductor deviceis attached in order to prevent short circuiting, however, the provisionof the insulating film 26 allows it to be disposed without suchbypassing. In addition, the insulating resin 13 and the insulatingadhesive means 17 protrude beyond the conductive patterns, therebyenabling to prevent short-circuiting between solder balls SD provided onthe back surface of the semiconductor device 10A.

Furthermore, the present invention is characterized in that the topsurface of the heat radiation electrode 15 is made protrusive beyond thetop surfaces of the pads 14.

As for a means to connect the pads 14 and the bonding electrodes 19, theuse of Au bumps or solder balls may be contemplated. An Au bump maycomprise at least one stage of an Au cluster, and the thickness thereofwould be about 40 μm for a one-stage bump and 70-80 μm for a two-stagebump. Since the height of the heat radiation electrode 15 surface isgenerally designed to match with the height of the pads 14 as shown inFIG. 2C, the distance “d” between the semiconductor chip 16 and the heatradiation electrode 15 is practically determined by the thickness of thebumps. Accordingly, the above space cannot be made any smaller than thethickness of the bumps in the case of FIG. 2C, so that it is notpossible to reduce the heat resistance given by this distance. However,as shown in FIG. 2, if the surface of the heat radiation electrode ismade protrusive beyond the surface of the pads by a thicknesssubstantially equal to the thickness of the bumps, this distance “d” maybe made smaller, so that the heat resistance between the semiconductorchip 16 and the heat radiation electrode 15 may be reduced.

The thickness of the solder bumps or solder balls is approximately 50 to70 μm, and in this case also, the distance “d” may be made smaller basedon the same principle. A brazing material such as solder has a goodwettability with the pads, so that when it is in a molten state, itspreads out over the entire surfaces of the pads, resulting in a smallerthickness. Further, since the gap between the bonding electrodes 19 andthe respective pads 14 is determined by the amount of protrusion of theheat radiation electrode 15, the thickness of the brazing material isdetermined by this amount of the protrusion so that the aforementionedrunning of solder may also be prevented. Accordingly, by the amount thebrazing material can be made thicker, the stress applied to the soldermay be more distributed, so that the deterioration due to heat cyclescan be minimized. In addition, by adjusting this amount of protrusion, acleaning fluid may be introduced into this gap.

This protrusive structure of the heat radiation electrode 15 isapplicable to all of the embodiments of the present inventionhereinafter explained.

(Embodiment 3)

FIG. 3 shows another semiconductor device 10B according to the presentinvention. FIG. 3A is a plan view thereof, and FIG. 3B is across-sectional view taken along the line A—A. Since this structure issimilar to that of FIG. 2, the following provides only the descriptionpertinent to those features that are different from the device in FIG.2.

In FIG. 2, the back surfaces of the pads 14 are used as the externalconnection electrodes as they are, however, in this embodiment, anintegral wiring 30 and an external connection electrode 31 integrallyformed with the wiring 30 are provided to each of the pads 14.

The rectangle shown by a dotted line represents the semiconductor chip16, and on the back surface of the semiconductor chip 16, the externalconnection electrodes 31 are disposed in a ring-like arrangement asshown. This arrangement is identical or similar to that of a known BGA.In order to alleviate the distortion at the connection points, they maybe formed in a wavy shape.

When the semiconductor chip 16 is disposed directly over the conductivepatterns 14, 30 and 31 and the heat radiation electrode 15, the patternsand the heat radiation electrodes are short-circuited via the backsurface of the semiconductor chip 16. Accordingly, the adhesive means 17has to be an insulating material, and any conductive material must notbe used.

The conductive pattern 32 on the first supporting member 1 shown in FIG.1 is connected to the external connection electrodes 31, and the backsurfaces of the pads 14 and the wirings 30 are covered by the insulatingfilm 26. The dotted circles indicated in the regions of the externalconnection electrodes 31 and the heat radiation electrode 15 representthe portions that expose from the insulating film 26.

Furthermore, since the external connection electrodes 31 are providedover the back surface of the semiconductor chip 16, the heat radiationelectrode 15 is designed to be smaller than the heat radiation electrode15 of FIG. 2. Accordingly, the insulating adhesive means 17 covers theheat radiation electrode 15, external connection electrodes 31 and thewirings 30. The insulating resin 13 would then form an integral bodywith the insulating adhesive means 17, thus, would cover the pads 14,the wirings 30, the semiconductor chip 16 and the solder (or bump) 20.

The present embodiment has an advantage in that, even when the number ofthe bonding pads 14 is extremely large and their size has to be reduced,the size of the external connection electrodes 31 may be madesufficiently large by connecting them via the wirings and rearrangingthem as the external connection electrodes. Also, the provision of thewirings alleviates the distortion stress applied to the bondingsections. Especially, wavy wirings are effective. The present inventionalso provides a feature that allows the space for the thickness of thesolder to be reserved by having the surface of the heat radiationelectrode protrude. Accordingly, with the provision of the wirings andthe design allowing the solder sections to have increased thickness, thereliability of the connections between the semiconductor chip 16 and thepads 14 may be improved.

Since the semiconductor chip 16 and the heat radiation electrode 15 areaffixed together by an insulating adhesive means 17, which is aninsulating material, there is a concern of thermal resistance. However,by constituting the insulating adhesive means by a silicon resin mixedwith fillers such as those made of silicon oxide or aluminum oxide thatcontribute to thermal conduction, the heat from the semiconductor chip16 may efficiently be conducted into the heat radiation electrode 15.

The distance between the heat radiation electrode 15 and thesemiconductor chip 16 may be made even by designing the fillers to havea same diameter. Therefore, where a very small separation is desired inconsideration with the thermal conduction, such a small separation mayeasily be formed by lightly applying a pressure to the semiconductorchip 16 while the insulating adhesive means is in a soft state. Since,in this embodiment, the use of aluminum oxide fillers having a diameterof 10 μm is assumed, the distance between the semiconductor chip 16 andthe heat radiation electrode 15 is retained substantially at 10 μm.

(Embodiment 4)

The fourth embodiment explains a manufacturing method of thesemiconductor devices 10A and 10B. Between the manufacturing methods ofthe semiconductor devices 10A and 10B, the only difference is whether itfabricates the pattern of FIG. 2 which includes only the heat radiationelectrode 15 and the pads 14, or the pattern of FIG. 3 whichadditionally includes the wirings 30 and the external connectionelectrodes 31, and the rest of the manufacturing steps are substantiallyidentical. Since either of the methods employs half-etching to formconvex patterns, the explanation will be provided herein with referenceto the manufacturing method of the semiconductor device 10B shown inFIG. 3. FIGS. 4 through 9 provide the cross-sectional views of FIG. 3Ataken along the line A—A.

First, as shown in FIG. 4, a conductive foil is provided. The thicknessof the foil is desirably between 10 μm and 300 μm, and herein, a rolledcopper foil in a thickness of 70 μm is used. Next, over the surface ofthis conductive foil 40, a conductive film 41 or a photo resist isformed as an etching mask. This pattern is identical to the pattern ofthe heat radiation electrode 15 of FIG. 3A.

Thereafter, the conductive foil 40 is half-etched via the conductivefilm 41 or the photo resist. The depth of etching should be shallowerthan the thickness of the conductive foil 40, and approximately equal tothe substantial thickness of the solder 20 (or bumps).

By this half-etching, a convex pattern of the heat radiation electrode15 manifests on the surface of the conductive foil 40. (FIG. 4)

Next, an etching mask PR is formed over the areas corresponding to thepatterns of the pads 14, the wirings 30, the external connectionelectrode 31 and the heat radiation electrode 15, and again, the foil ishalf-etched. There are two types of formation methods for forming theportion of the etching mask corresponding to the region of the heatradiation electrode 15, one for forming PR1 and another for forming PR2,and depending on the method selected, the resultant geometry of the sidesurfaces of the heat radiation electrode slightly differs. Where amaterial having a slow etching rate such as Ni is selected as theconductive film, an overhang is formed, thus, the anchor effect can beexpected.

At the layer below the etching mask, a conductive film made of Au, Ag,Pd or Ni etc. is formed over at least the locations corresponding to thepads. This film is formed in order to allow bonding.

The conductive foil 40 is then half-etched using the etching mask PR.The depth of this etching is arbitrary as long as it is shallower thanthe remaining thickness of the conductive foil 40. A shallower etchingdepth allows the formation of a finer pattern.

By this half-etching, the convex patterns of the pads 14, the wirings 30and the external connection electrodes 31 manifest, and the heatradiation electrode 15 that has been half-etched in the previous stepmanifests as being protrusive beyond the pads 14, the wiring 30 and theexternal connection electrodes 31. (FIG. 5)

The conductive foil 40 used herein is a Cu foil mainly made of Cu, whichhas been formed by rolling. This is because a rolled Cu foil is superiorin flexibility. However, it may also be a conductive foil made of Al oran Fe—Ni alloy, or a laminate of Cu—Al, Al—Cu—Al or Cu—Al—Cu. Thelaminate of Al—Cu—Al or Cu—Al—Cu, especially, can prevent warping causedby a difference in thermal expansion coefficients.

The insulating adhesive means 17 is then applied onto the regioncorresponding to the rectangle indicated by a dotted line in FIG. 3.This insulating adhesive means 17 is provided in and over the isolationtrench 22 between the heat radiation electrode 15 and the externalconnection electrodes 31, an isolation trench between the heat radiationelectrode 15 and the wirings 30, and isolation trenches between wirings30.

The semiconductor chip 16 is then affixed to the region on which theinsulating adhesive means 17 has been provided, and the bondingelectrodes 19 of the semiconductor chip 16 and the pads 14 areelectrically connected. In the embodiment shown in the diagrams, sincethe semiconductor chip 16 is mounted with its face down, the solder SD1or the bumps shown in FIG. 16 are used as the connecting means.

Herein, there is a great significance in having the surface of the heatradiation electrode 15 protrude beyond the surfaces of the pads 14 bythe distance “d”.

An Au bump comprises at least one stage of an Au cluster, so that thethickness of which would be 40 μm for one stage, and 70 to 80 μm for twostages. Accordingly, by having the surface of the heat radiationelectrode 15 protrude beyond the surfaces of the pads 14 by thesubstantial thickness of the bumps, the gap “d” may be reduced.

In the case of solder bumps or solder balls, the thickness would beapproximately 50 to 70 μm, and the gap may be reduced based on the sameprinciple. Since a brazing material such as solder has a goodwettability with the pads, it spreads out on the surfaces of the padswhen it is in a molten state, thereby reducing its thickness. However,since the spacing between the bonding electrodes and the pads isdetermined by the amount of protrusion of the heat radiation electrode,the thickness of the brazing material would be determined by this amountof protrusion, so that spreading-out of solder is also restrained.Accordingly, by the extent the thickness of the brazing material can beincreased, the stress applied to the solder may be more distributed,thereby suppressing the deterioration caused by heat cycles.

In this bonding process, since the pads 14 are integral with theconductive foil 40, and the back surface of the conductive foil 40 isflat, the device can be abutted to the table of the bonding machine bythe plane. Accordingly, if the conductive foil 40 is perfectly fixedonto the bonding table, the pads 14 and the solder balls formed on thesemiconductor chip 16 are all abutted in place, so that solderingfailures would not occur. The fixation to the bonding table may beachieved by, for example, providing a plurality of vacuum holes over theentire surface of the table. There are other alternative methods forproviding these connections, which will be explained at the end of thissection with reference to FIG. 16.

The semiconductor chip may be mounted without using a supportingsubstrate, and the solder balls are used instead of metal thin lines, sothat the semiconductor chip 16 may be disposed at a position lower bythat extent. Accordingly, the outer thickness of the package may bereduced as later explained.

Where an under fill is used as the insulating adhesive means 17, theunder fill is introduced after the semiconductor chip 16 and the pads 14are attached. (FIG. 6)

The insulating resin 13 is then formed over the entire region includingthe semiconductor chip 16. For the insulating resin, either athermoplastic resin or a heat-curable resin may be used.

It may be formed via transfer molding, injection molding, dipping orcoating. For a heat-curable resin such as epoxy resin, transfer moldingmay be employed, and for a thermoplastic resin such as liquid crystalpolymer or polyphenylene sulfide etc., injection molding may beemployed.

In the present embodiment, the thickness of the insulating resin isadjusted so that its top end comes at approximately 100 μm from the backsurface of the semiconductor chip 16. This thickness may be made largeror smaller depending on the desired strength of the semiconductordevice. Alternatively, the back surface of the semiconductor chip maybeexposed. In this case, radiator fins may be attached thereon, or directexternal dissipation of the heat generated by the semiconductor chip maybe attempted.

Since the pads 14, wirings 30, the external connection electrodes 31 andthe heat radiation electrode 15 are all integral with the conductivefoil 40 that is in a form of a sheet, these copper foil patterns wouldnever be displaced during the resin injection step as long as theconductive foil 40 itself is not displaced. In addition, unlike leadframes, these conductive patterns would never generate flashes of theresin.

As explained in the above, within the insulating resin 13, the pads 14,wirings 30, external connection electrodes 31 and the heat radiationelectrode 15 that are formed as convex features are embedded along withthe semiconductor chip 16, and the portion of the conductive foil 40below its convex features is exposed from the back surface. (FIG. 7)

Thereafter, the portion of the conductive foil 40 exposed on the backsurface of the insulating resin 13 is eliminated, thereby separating thepads 14, wirings 30, external electrodes 31 and heat radiation electrode15 into individual elements.

For this separation step, various approaches may be contemplated. Forexample, they may be separated by etching the back surface, or bypolishing or grinding, or even by the combination thereof. For example,where the grinding is performed until the insulating resin 13 isexposed, there is a risk of having residues or stretched metal particlesfrom the ground conductive foil 40 encroach into the insulating resin 13or the insulating adhesive means 17. Accordingly, by using an etchingapproach, the separation may be achieved without having the metalresidues from the conductive foil 40 encroach into the surface of theinsulating resin 13 or the insulating adhesive means 17 located betweenthe Cu patterns. In this way, short-circuiting between the patternsarranged at fine intervals may be prevented.

In a case where a plurality of units, each comprising a singlesemiconductor device 10B, are integrally formed, a dicing step isadditionally performed after this separation step.

Although a dicing apparatus is used herein to individually separate theunits, it is also possible to perform this step bychocolate-bar-breaking, pressing or cutting.

According to this embodiment, after separating the Cu patterns, aninsulating film 26 is formed over the patterns 14, 30, 31 and 15, andthe insulating film 26 is then patterned so as to expose the portionsindicated by the dotted circles shown in FIG. 3A. Thereafter, it isdiced at the sections indicated by arrows into individual semiconductordevices 10B.

The solder balls 42 may be formed either before or after the dicingstep.

According to the manufacturing method above, a thin and small packagewith a superior heat dissipation capability is fabricated, in which thebonding pads, wirings, external connection electrodes, heat radiationelectrode and semiconductor chip are embedded within the insulatingresin.

As shown in FIG. 9, the molding may alternatively be achieved by usingthe insulating adhesive means 17, without using the insulating resin 13.The patterns PTN shown in FIG. 10 represent the pads, wirings, externalconnection electrodes, and the hatched regions shown thereon representformation patterns of the film for preventing solder running. This filmserves to prevent solder running, and at the same time, it is applied tothe other regions to improve the adhesion of the insulating adhesivemeans. As for alternatives, patterns A through E are illustrated,however, any other pattern may be selected. The solder-runningprevention film may also be formed over the entire region other than theregions for solder connections.

The effects obtained by the above manufacturing method will now beexplained.

First, since the conductive patterns are half-etched and supportedintegrally with the conductive foil, a substrate that has conventionallybeen employed for supporting is unnecessitated.

Second, since the convex conductive patterns are formed by half-etchingthe conductive foil, it is possible to form finer conductive patterns.Accordingly, their widths and intervals may be minimized, allowing theformation of a package having a smaller two-dimensional size.

Third, since the device may be constituted by conductive patterns, asemiconductor chip, connection means and a molding material, thestructure would include only the elements that are truly essential,eliminating the excessive use of materials, thus, a thin and smallsemiconductor device may be realized with a substantially reduced cost.

Fourth, since the pads, wirings, external connection electrodes and heatradiation electrode are formed as convex portions through half-etching,and the separation to individual elements is performed after the moldingstep, tie-bars and suspension leads would not be necessary. Accordingly,the necessity for the formation of tie-bars (suspension leads), andcutting step of the tie-bars (suspension leads) are completelyeliminated in the present invention.

Fifth, since the conductive foil is eliminated from the back surface ofthe insulating resin to separate the conductive patterns after theconvex conductive patterns are embedded within the insulating resin,flashes of the resin formed between leads as those present in theconventional lead frames can be eliminated.

Sixth, since the semiconductor chip is affixed with the heat radiationelectrode via the insulating adhesive means, and the head-dissipatingelectrode is exposed from the back surface, the heat generated by thesemiconductor device can be dissipated efficiently from the surface ofthe semiconductor device to the heat radiation electrode. Furthermore,by mixing fillers such as those made of silicon oxide or aluminum oxideinto the insulating adhesive means, the heat-dissipating capabilitythereof may further be improved. By uniformly designing the filler size,the spacing between the semiconductor chip 16 and the conductivepatterns may be evenly retained.

(Embodiment 5)

The fifth embodiment is provided for illustrating a semiconductor device10A, 10B to which a metal plate 23 is affixed and a semiconductor moduleusing the same. FIG. 1 shows this type of semiconductor module (FCA) 50.The semiconductor device mounted thereto is the semiconductor device 10Bshown in FIG. 3.

First, a first supporting member 11 constituted by a flexible sheet willbe explained. In the present embodiment, it comprises a first PI sheet51, a first adhesion layer 52, a conductive pattern 53, a secondadhesion layer 54 and a second PI sheet 55 that are sequentiallylaminated from the bottom. When forming the conductive pattern inmultiple layers, additional adhesion layers may be used, and upper andlower layers of the conductive pattern may be electrically connectedthrough contact holes. Provided in this first supporting member 11 is afirst opening 12 which would allow at least a metal plate 23 to beexposed as shown in FIG. 1C.

A second opening 56 is also formed in order to expose the conductivepattern. The second opening 56 may entirely expose the correspondingconductive pattern 32, or may partially expose only the portion forforming connections. For example, the second PI sheet 55 and the secondadhesion layer 54 may entirely be eliminated, or, as shown in thefigure, while entirely eliminating the second PI sheet, the secondadhesion layer 54 may partially be eliminated only at the locationsrequired to be exposed. According to the later manner, running of thesolder 27 may be prevented.

The significance of this semiconductor device of the present inventionis in that a metal plate 23 is adhered to the back surface of the heatradiation electrode 15. The significance of the semiconductor module ofthe present invention is in that the metal plate 23 and the back surfaceof the first supporting member would become substantially within thesame plane.

The thickness of the metal plate 23 is determined according to thethicknesses of the first supporting member 11 and the fixation plate 25.The thicknesses are respectively determined in a manner so that themetal plate 23 exposed from the first opening 12 and the back surface ofthe first supporting member 11 can be substantially within a same planewhen the pads 14 and the conductive pattern 32 are affixed togetherthrough the solder balls 27. Accordingly, the metal plate 23 maybeabutted to the second supporting member or abutted and adhered to thefixation plate 25 provided on the second supporting member.

Several examples of this connection structure are given below.

In the first example of the structure, a light-weight metal plate suchas the one made of Al or stainless steel etc., or a ceramic substrate isused as the second supporting member 24, and the metal plate 23 whichhas been affixed on the back surface of the semiconductor device 10 isabutted thereto. That is, in this structure, the abutment to the secondsupporting member 24 is provided without the use of the fixation plate25. The fixation between the heat radiation electrode 15 and the metalplate 23, and between the metal plate 23 and the second supportingmember 24 is achieved by a brazing material such as solder etc. or aninsulating adhesive means containing fillers having a superior thermalconductivity.

In the second example, the structure employs a light-weight metal platesuch as the one made of Al or stainless steel etc. or a ceramicsubstrate as for the second supporting member 24, and a fixation plate25 is formed thereon, and this fixation plate 25 and the metal plate 23is affixed together.

Where an Al plate is used as the second supporting member 24 forexample, the fixation plate 25 is preferably the one made of Cu. This isbecause Cu can be plated over Al. This may be formed in a thickness of,up to about 10 μm. In addition, since it is a plated film, it may beformed in intimate contact with the second supporting member 24, makingthe thermal resistance between the fixation plate 25 and the secondsupporting member 24 extremely small. Alternatively, a conductive pastmay be applied to form the fixation plate 25.

The Cu fixation plate 25 and the Al substrate may instead be adheredusing an adhesive, however, in this case the thermal resistance wouldbecome larger.

Where a ceramic substrate is used as the second supporting member 24,the fixation plate 25 is formed on an electrode formed by print-baking aconductive paste.

The second supporting member 24 and the first supporting member 11 areadhered together via a third adhesion layer 57.

For instance;

-   First PI sheet 51: 25 μm-   Second PI sheet 55: 25 μm-   First through third adhesion layers 52, 54, 57: 25 μm after being    baked (an acrylic adhesive is used)-   Solder balls 27: 50 μm;-   Conductive pattern 53: 25 μm-   Fixation plate 25: approximately 25 μm.    Where the thicknesses of the respective films are adjusted in this    way, then after affixing the semiconductor device onto the first    supporting member 11, the second supporting member 24 having the    fixation plated 25 formed thereon would be readily adhered.

Where a module is provided, in which the second supporting member 24 isattached to the first supporting member 11, and the semiconductor device10 is placed within an opening 56 provided in this module and thensoldered, the soldering may be performed at once without promotingconnection failures.

Accordingly, the heat generated by the semiconductor chip 16 may bedissipated into the second supporting member 24 via the heat-dissipatingplate 15, metal plate 23 and fixation plate. Moreover, since it providesa substantial reduction in the thermal resistance compared to that ofthe conventional art structure (FIG. 18B), the driving current and thedriving frequency of the semiconductor chip 16 can be maximized. Theback surface of this second supporting member 24 may be attached to theactuator 107, bottom of the casing 101 or the arm 105 shown in FIG. 17.Therefore, the heat from the semiconductor chip can ultimately beemitted to the outside via the casing 101. Accordingly, even if thesemiconductor module is mounted within the hard disk 100, thetemperature of the semiconductor chip itself is kept relatively low, sothat the read/write speed of the hard disk 100 can be furtheraccelerated. This FCA may be mounted on an apparatus other than a harddisk. In this case, the second supporting member should be abutted to amember of the apparatus having a small thermal resistance. Where it ismounted in any other apparatus, a printed board or a ceramic substratemay also be used instead of the flexible sheet.

(Embodiment 6)

The sixth embodiment is provided to illustrate a semiconductor device10C in which the heat radiation electrode 15 is made protrusive tosubstitute the metal plate, and a semiconductor module 50A using thesame. FIG. 11 shows a structure in which the heat radiation electrode15A protrudes beyond the top surfaces and the back surfaces of the pads14 as if the heat radiation electrode 15 and the metal plate 23 areconstituted by an integral element.

First, the manufacturing method thereof will be explained with referenceto FIGS. 12 through 14. Its manufacturing steps corresponding to thesteps illustrated in FIGS. 4 through 8 are identical and thedescriptions for these steps would not be repeated.

FIG. 12 is showing the conductive foil 40 being covered by theinsulating resin 13, and on the portion corresponding to the heatradiation electrode 15, a photo resist PR is formed. When thisconductive foil 40 is etched via the photo resist PR, the resultant heatradiation electrode 15A would have a structure which protrudes beyondthe back surfaces of the pads 14. Alternatively, a conductive film madeof Ag or Au etc. may be selectively formed and used as a mask instead ofthe photo resist PR. This film would function also as an anti-oxidizingfilm.

In the structure such as the one shown in FIG. 1 in which the metalplate 23 is adhered, since the metal plate 23 is extremely thin (i.e.125 μm), the workability is extremely poor. On the other hand, where theheat radiation electrode 15A is etched to have the protrusive structure,the attaching step of the metal plate 23 may be eliminated.

Next, as shown in FIG. 14, after the pads 14, wirings 30 and externalconnection electrodes 31 are completely separated, the insulating film26 is formed, and the portions for providing solder balls are exposed.After it is affixed via the solder balls 42, it is diced at the sectionsindicated by arrows.

The isolated semiconductor device is then mounted on the firstsupporting member 11 as shown in FIG. 11. Thereafter, the secondsupporting member 24 is attached thereto as previously mentioned. Atthis point, since the heat radiation electrode 15A is protrusive, it canbe readily connected to the fixation plate 25 via soldering etc.

Shown in FIG. 14B is a structure in which the back surface of thesemiconductor chip 16 is exposed from the insulating resin. For example,by performing the molding step while abutting the back surface of thesemiconductor chip to the top mold, then the molded structure such asthe one shown may be obtained.

(Embodiment 7)

The seventh embodiment is provided to illustrate another semiconductordevice. FIG. 15A shows a plan view of the semiconductor device accordingto the present invention, and FIG. 15B shows a cross-sectional view ofFIG. 15A taken along the line A—A.

According to the present invention, a first heat radiation electrode 70Aand a second heat radiation electrode 70B are disposed substantially ina same plane, and along the peripheries thereof, pads 14 are arranged.The back surfaces of these pads 14 themselves serve as the externalconnection electrodes, however, the re-arranged type of wirings shown inFIG. 3 may instead be employed. Between the chips, at least one bridge71 is disposed. At the both ends of the bridges 71, pads 14 areintegrally formed, and these pads 14 too are connected to the bondingelectrodes 19.

Over the first heat radiation electrode 70A which protrudes upwardly, afirst semiconductor chip 16A is affixed, and over the second heatradiation electrode 70B which similarly protrudes upwardly, a secondsemiconductor chip 16B is affixed, and they are connected via solder.

As apparent from the above explanation, by half-etching the conductivefoil, and performing the molding of the insulating resin 13 before thefoil is completely separated, the risk of having the bridges 71 falldown or slip out may be eliminated.

As in the present embodiment, a plurality of chips may be packaged intoa single package.

The embodiments described heretofore are provided in order to illustratethe structures designed in consideration with the heat-dissipatingcapability of a single read/write amplifying IC. However, where theapplications to various types of apparatus are contemplated, there maybe a case in which the heat-dissipating capability of a plurality ofsemiconductor chips must be considered. Of course, it is possible topackage them into separate, individual packages, however, the pluralityof the semiconductor chips may also be packaged into one package asillustrated in FIG. 15.

The metal plates may of course be provided in either the structure inwhich they are attached to the heat radiation electrodes as shown inFIG. 1 or the structure in which the heat radiation electrodesthemselves are designed to have the protrusive structure as shown inFIG. 11. These devices may be mounted on a flexible sheet or a flexiblesheet having the second supporting member attached thereon.

FIG. 16 shows a series of diagrams for illustrating several methods thatare applicable to any of the embodiments for providing connectionbetween bumps B formed on the semiconductor chip 16 and the pads 14. Prepresents a plated film made of Au, Ag or the like formed if necessary.

FIG. 16A illustrates an ACP (anisotropic conductive paste/film) methodin which the electrical conduction is achieved by providing conductiveparticles between the bump B and the pad 14 (or plated film P), andapplying pressure.

FIG. 16B illustrates an SBB (stand bump bonding) method in which, as thebump B and the pad 14 (or plated film) are connected, conductive pasteCP is simultaneously provided at the periphery.

FIG. 16C illustrates an ESC (epoxy encapsulated solder connection)method in which, as the bump B is pressure-welded, molten solder SD issimultaneously provided at the periphery.

FIG. 16D illustrates an NCP (non-conductive paste) method in which aninsulating adhesive means is provided around the bump B which has beenpressure-welded to achieve electrical conduction.

FIG. 16E illustrates a GGI (gold-gold interconnection) method in whichan Au bump and a plated Au film P are connected by ultrasonic wave.

FIG. 16F illustrates a solder bump method in which the connection isachieved through soldering, and an insulating adhesive means or an underfill is introduced into the gap. The disclosure herein employs thismethod.

The embodiments described above are explained with a flexible sheet as asubstrate, however, a ceramic substrate, a printed board, a flexiblesheet, a metal substrate or a glass substrate etc. can also be appliedto the substrate of the present invention.

As listed above, there are a variety of connecting methods available,however, in consideration with the connection strength, a method shouldbe selected from the above. A structure such as the one from the abovemay also be used for the connections between the back surfaces of theexternal connection electrodes and the first supporting member 11.

As apparent from the above description, according to the presentinvention, the distance between the semiconductor chip and the heatradiation electrode may be made smaller by having the surface of theheat radiation electrode protrude beyond the surfaces of the pads.Especially, the distance between the bonding electrodes and the pads isdetermined by the protruding amount of the heat radiation electrode, sothat the thickness of the brazing material is determined by thisprotruding amount. Accordingly, by the amount the thickness of thebrazing material can be increased, the stress applied to the solder canbe more distributed, thereby enabling to suppress the deterioration byheat cycles.

The present invention also provides an advantage in that the mounting ofthe device on an FCA can be facilitated by providing the semiconductordevice in which the metal plate protrudes beyond the back surfaces ofthe external connection electrodes or the pads by affixing a metal plateto a heat radiation electrode exposed from the back surface of thepackage.

Especially, by providing an opening to the FCA so as to allow the backsurface of the FCA and the heat radiation electrode of the semiconductordevice to be within a same plane, the abutment to the second supportingmember can be readily achieved.

By using Al as for the second supporting member material and by formingthereon a fixation plate made of Cu, and affixing the heat radiationelectrode or the metal plate to this fixation plate, the heat generatedby the semiconductor chip may be externally dissipated via the secondsupporting member.

Accordingly, the temperature rise of the semiconductor chip may beprevented, allowing the device to operate at a higher performance levelclose to its inherent capability. Especially, such an FCA used in a harddisk is capable of providing efficient external emission of heat so thatthe read/write speed of the hard disk may be increased.

1. A hard disk comprising a semiconductor device, wherein thesemiconductor device including: a semiconductor chip integrally moldedby an insulating resin in a face-down state; a pad electricallyconnected to a bonding electrode of the semiconductor chip and providedto expose from the insulating resin; a heat radiation electrode disposedon the surface of the semiconductor chip and provided to expose from theinsulating resin; and a connecting means which connects the bondingelectrode and the pad, wherein the top surface of the heat radiationelectrode protrudes beyond the top surface of the pad, and by the amountof the protrusion, the thickness of the connecting means is practicallydetermined.
 2. A hard disk comprising a semiconductor module, whereinthe semiconductor module including: a first supporting member provided aconductive pattern; a semiconductor device including: a semiconductorchip electrically connected to the conductive pattern and integrallymolded by an insulating resin in a face-down state; a pad electricallyconnected to a bonding electrode of the semiconductor chip and theconductive pattern, and provided to expose from the insulating resin; aheat radiation electrode disposed on the surface of the semiconductorchip and provided to expose from the insulating resin; a connectingmeans which connects the bonding electrode and the pad; an openingportion provided in the first supporting member at a locationcorresponding to the heat radiation electrode; and a metal plate affixedto the heat radiation electrode in the opening portion, wherein the topsurface of the heat radiation electrode protrudes beyond the top surfaceof the pad, and by the amount of this protrusion, the thickness of theconnecting means is practically determined.
 3. A hard disk comprising asemiconductor device, wherein the semiconductor device including: asemiconductor chip integrally molded by an insulating resin in aface-down state; a pad electrically connected to a bonding electrode ofthe semiconductor chip; an external connection electrode extending via awiring integral to the pad and provided to expose from the insulatingresin; a heat radiation electrode disposed on the surface of thesemiconductor chip; and a connecting means which connects the bondingelectrode and the pad, wherein the top surface of the heat radiationelectrode protrudes beyond the top surface of the pad, and by the amountof this protrusion, the thickness of the connecting means is practicallydetermined.
 4. A hard disk comprising a semiconductor module, whereinthe semiconductor module including: a first supporting member having aconductive pattern; a semiconductor device including: a semiconductorchip electrically connected to the conductive pattern and integrallymolded by an insulating resin in a face-down state; a pad electricallyconnected to a bonding electrode of the semiconductor chip; an externalconnection electrode provided via a wiring integral to the pad and theconductive pattern, and provided to expose from the insulating resin; aheat radiation electrode disposed on the surface of the semiconductorchip and provided to expose from the insulating resin; a connectingmeans which connects the bonding electrode and the pad; an openingportion provided in the first supporting member at a locationcorresponding to the heat radiation electrode; and a metal plate affixedto the heat radiation electrode in the opening portion, wherein the topsurface of the heat radiation electrode protrudes beyond the top surfaceof the pad, and by the amount of this protrusion, the thickness of theconnecting means is practically determined.